No pulsar kicks from deformed neutrinospheres - art. no. 023005.

In a supernova core, magnetic fields cause a directional variation of the n eutrino refractive index so that resonant flavor oscillations would lead to a deformation of the "neutrinosphere" for, say, tau neutrinos. The associa ted anisotropic neutrino emission was proposed as a possible origin of the observed pulsar proper motions. We argue that this effect was vastly overes timated because the variation of the temperature over the deformed neutrino sphere is not an adequate measure for the anisotropy of neutrino emission. The neutrino flux is generated inside the neutron star core and is transpor ted through the atmosphere at a constant luminosity, forcing the temperatur e gradient in the atmosphere to adjust to the inflow of energy from below. Therefore, no emission anisotropy is caused by a deformation of the neutrin osphere to lowest order. An estimate of the higher-order corrections must t ake into account the modified atmospheric temperature profile in response t o the deformation of the neutrinosphere and the corresponding feedback on t he core. We go through this exercise in the framework of a simplified model which can be solved analytically. [S0556-2821(98)02524-7].